1. Field of the Invention
The present invention relates to an elastic sheet structure having an electrical continuity function and to a printed circuit board structure.
2. Description of the Related Art
A conventional printed circuit board structure is illustrated in FIG. 9. As shown in FIG. 9, a plurality of rubber contacts 102 each having an On/Off switching function moderated by elastic deformation are formed integrally at predetermined positions of a silicon rubber sheet 100. A movable contact 104 is fixed to the reverse surface of each rubber contact 102. A printed circuit board (PCB) 110, at which fixed contacts 106, a connector 108, and the like are assembled, is disposed at the reverse surface side of the silicon rubber sheet 100. A widthwise direction dimension P of the printed circuit board 110 is set to be substantially the same as a widthwise direction dimension Q of the silicon rubber sheet 100.
In accordance with the above-described structure, when the rubber contact 102 provided at the silicon rubber sheet 100 is pressed, the rubber contact 102 elastically deforms and sinks in, such that the movable contact 104 is displaced in the direction of pushing and is set in a state of being electrically continuous with the fixed contact 106.
However, the above-described conventional printed circuit board structure is structured from the standpoint that only a contact function and an On/Off switching function moderated by elastic deformation are required of the silicon rubber sheet 100, and electrical flow continuity between the rubber contacts 102 is ensured separately at the printed circuit board 110. Therefore, the printed circuit board 110 must be of a size such that the printed circuit board 110 can cover at least the range over which all of the rubber contacts 102 are disposed as seen in plan view. Thus, the printed circuit board 110 is made large, and consequently, the space required for placement of the printed circuit board 110 also is large. As a result, disadvantages such as a decrease in the number of degrees of freedom in design, and increases in the size, weight and cost of the manufactured product arise.
In view of the aforementioned, an object of the present invention is to provide an elastic sheet structure having an improved electrical continuity function and a printed circuit board structure in which the number of degrees of freedom in design can be increased, and which can be made smaller-sized, lighter-weight, and lower-cost.
In a first aspect of the present invention, an elastic sheet structure having an (improved) electrical continuity function comprises: an elastic sheet member formed of a non-conductive material and formed in a sheet-shaped form, and having push portions which, when pushed, elastically deform and displace movable contacts, which are provided at reverse surface sides of the push portions, in a direction of pushing by a predetermined distance so as to make the movable contacts electrically continuous with fixed contacts; and continuity members provided at the elastic sheet member and formed of a conductive material and formed in a wire-like pattern, starting end portions of the continuity members being connected to the movable contacts or the fixed contacts, and final end portions of the continuity members being exposed to an exterior of the elastic sheet member for connection to a printed circuit board which is provided separately and independently at a reverse surface side of the elastic sheet member.
In a second aspect of the present invention, the starting end portions of the continuity members of the above-described elastic sheet structure having an improved electrical continuity function are disposed so as to be dispersed at optional plural places in accordance with places at which the push portions are set, and the final end portions of the continuity members are disposed intensively at a small number of specific places.
In a third aspect of the present invention, a printed circuit board structure comprises: an elastic sheet member formed of a non-conductive material and formed in a sheet-shaped form, and having push portions which, when pushed, elastically deform and displace movable contacts, which are provided at reverse surface sides of the push portions, in a direction of pushing by a predetermined distance so as to make the movable contacts electrically continuous with fixed contacts; a printed circuit board fixed to a reverse surface side of the elastic sheet member; and continuity members formed of a conductive material and formed in a wire-like pattern, starting end portions of the continuity members being connected to the movable contacts or the fixed contacts, and final end portions of the continuity members being connected to the printed circuit board.
In a fourth aspect of the present invention, the starting end portions of the continuity members of the above-described printed circuit board structure are disposed so as to be dispersed at optional plural places in accordance with places at which the push portions are set, and the final end portions of the continuity members are disposed intensively at a small number of specific places.
In accordance with the first aspect, when the push portions provided at the elastic sheet member are pushed, the movable contacts provided at the rear surface thereof are displaced in the direction of pushing by a predetermined distance, and become electrically continuous with the fixed contacts. The starting end portions of the continuity members are connected to the movable contacts or the fixed contacts of the elastic sheet member. The final end portions of the continuity members are exposed to the exterior of the elastic sheet member, in order to be connected to a printed circuit board which is provided independent and separately at the reverse surface side of the elastic sheet member. Accordingly, as a result of the above-described operation, electric flow continuity paths are ensured.
In accordance with the present invention, the continuity members, which are formed of a conductive material and are formed in a wire-like pattern (this xe2x80x9ca wire-like patternxe2x80x9d includes a complicated a net-work like pattern, too), are provided at the elastic sheet member, which is formed of a non-conductive material and is formed in a sheet-shaped form. The final end portions of the continuity members are connected to the printed circuit board. Thus, there is no need to make the printed circuit board be a size of an extent which can cover the range at which all of the push portions are provided.
In other words, in the present aspect, by transferring the function of the electric continuity (by way of the electrical flow continuity paths), from being provided at the printed circuit board in the conventional art, to being provided at the elastic sheet member which is formed basically of a non-conductive material, the functions of the printed circuit board can be simplified as a whole.
Accordingly, by applying the invention based on the present aspect, it suffices for the printed circuit board to be able to cover only the regions of connection thereof with the final end portions of the continuity members. Thus, the printed circuit board can be made compact, and the space required for placement thereof can be reduced. In this way, the degrees of freedom in design can be increased, and a manufactured product can be made compact and lighter weight. This leads to a reduction in manufacturing costs as well.
In the second aspect of the present invention, the starting end portions of the continuity members are disposed so as to be dispersed at optional plural places in accordance with places at which the push portions are set, and the final end portions of the continuity members are disposed intensively at a small number of specific places. Accordingly, in accordance with the present aspect, no matter how many plural places the push portions are dispersed at, it suffices for the printed circuit board itself to exist at a range which can cover the small number of specific places where the final end portions of the continuity members are disposed. Accordingly, the more pushing members that are provided, the more effective is the present invention.
The third aspect of the present invention applies the concept of the above-described first aspect to a printed circuit board structure. Namely, in accordance with the present aspect, a printed circuit board structure is formed to include a printed circuit board and the elastic sheet member having an improved electrical continuity function based on the first aspect.
Because the elastic sheet structure having an improved electrical continuity function based on the first aspect is directly applied in the present aspect, the above-described excellent effects based on the first aspect can similarly be obtained in the present aspect. Accordingly, in the present aspect as well, the printed circuit board can be made compact, and the space required for placement thereof can be reduced. In this way, the degrees of freedom in design can be increased, and a manufactured product can be made compact and lighter weight. This leads to a reduction in manufacturing costs as well.
The fourth aspect of the present invention applies the concept of the above-described second aspect to a printed circuit board structure. Namely, in accordance with the present aspect, a printed circuit board structure is formed to include a printed circuit board and the elastic sheet member having an improved electrical continuity function based on the second aspect.
Because the elastic sheet structure having an improved electrical continuity function based on the second aspect is directly applied in the present aspect, the above-described excellent effects based on the second aspect can similarly be obtained in the present aspect. Accordingly, in the printed circuit board structure, the printed circuit board can be made compact, and the space required for placement thereof can be reduced. In this way, the degrees of freedom in design of the printed circuit board structure can be increased, and a manufactured product can be made compact and lighter weight. This leads to a reduction in manufacturing costs as well.